Some downhole drilling tools contain an outer housing with a mandrel positioned therein. In such a tool, the mandrel may be tubular and may define a mandrel bore. The mandrel bore may define a bore fluid path allowing fluid flow from drilling pumps to pass through downhole drilling tool. The annular area formed between the outer surface of the mandrel and the inner surface of the outer housing may define an annular fluid path. Some downhole tools may contain both a bore fluid path and an annular fluid path. It may be desirable to control or limit fluid flow from the bore fluid path to the annular fluid path or vice versa. One method of achieving this is to install nozzles in a barrier portion between the bore fluid path and the annular fluid path, such that the desired total flow area (TFA) between bore fluid path and annular fluid path may be configured during downhole tool assembly. In a traditional tool, the nozzles may be positioned for access should the downhole tool set-up change, such as to require a different TFA, a tubular connection between the outer sub and another tubular of the tool string may be broken out allowing access such that the nozzles may be removed and replaced. It may even be possible to change a TFA configuration whilst downhole tool is located on the rig floor, however, breaking a threaded connection between tubular members to change the nozzle TFA on the rig floor is time consuming and requires the use of large equipment.